Glacier will go ahead with Gunsight Lake project, adds whitefish

Glacier National Park will go ahead with an effort to remove non-native fish from Gunsight Lake, replacing them with native westslope cutthroat trout, mountain whitefish and bull trout.

The Park Service added whitefish to the restocking effort as another native food source for the bull trout, which are a predatory fish, it said in a Finding of No Significant Impact.

Gunsight Lake currently has a population of non-native rainbow trout, stocked there decades ago.

The rainbow trout will be removed from the lake using an EPA registered and approved fish toxicant, rotenone. While rotenone degrades naturally with sunlight and water movement, detoxification will be hastened with a neutralizing agent. The neutralizing agent, potassium permanganate, is widely used for the treatment of municipal drinking water and wastewater.

The Park Service will then re-stock the lake starting next year from pure native fish stocks that live in drainages close to Gunsight Lake.

The work will begin next month.

Some local and national environmental groups raised objections to the project, with worries about the impacts to wilderness, as a motorized boat will be used to spread the rotenone and a helicopter will be used to bring the boat in and out of the lake.

They also raised concerns about re-stocking a lake that would have been historically, fishless.

But the Park Service found the impacts to be temporary and the overall effort to be worthwhile in its continued effort to move native species further up drainages as a way to preserve populations in the face of climate change.

Gunsight Lake is a high mountain lake that is tucked along the Continental Divide, one of the most popular places to camp in Glacier.

There will be some temporary closures as a result of the work. The backcountry campground at the lake will be closed from Sept. 1 through next spring and the trail will be closed while the fish removal work is being done, which should take about a week.

The lake will re-open to recreational fishing, with catch-and-release regulations. The re-stocking effort could take several years.

The project is part of an overall effort by Glacier to re-establish native fish populations in high country lakes.

It recently did a similar project at Camas Lake, where non-native Yellowstone cutthroat were removed using rotenone and the lake was re-stocked with native westslope cutthroat trout.

They also stocked Grace Lake with native bull trout. That has proven successful as well.